“Homosexuality is assuredly no advantage, but it is nothing to be ashamed of, no vice, no degradation; it cannot be classified as an illness; we consider it to be a variation of the sexual function, produced by a certain arrest of sexual development. Many highly respectable individuals of ancient and modern times have been homosexuals, several of the greatest men among them. (Plato, Michelangelo, Leonardo da Vinci, etc). It is a great injustice to persecute homosexuality as a crime – and a cruelty, too.”

— Sigmund Freud in a letter he wrote in 1935 to a mother seeking treatment for her gay son
[via letters of note]